1. Fields of the Invention
This invention is directed to a sphygmomanometer utilized in the measuring of a person's blood pressure based on listening for Korotkoff sounds, particularly to a sphygmomanometer of the type adapted for use in measuring the blood pressure of the user by oneself.
2. Description of the Prior Art
One known sphygmomanometer of this type has been proposed in Japanese Utility Model Early Publication (KOKAI) No. 51-8687 in which a cuff is secured to a main body or housing accommodating means for detecting and indicating a user's blood pressure. In taking the blood pressure by the use of this instrument, the cuff is required to be wrapped around the user's arm extended generally horizontally in such a manner as to place the main body on the arm with its upper surface facing upwardly for the purpose of arranging a manometer on the upper side of the main body to be readily observed by the user oneself. However, due to the inherent nature of the main body being in heavy construction, the main body is likely to slip down on the backside of the arm or to be shifted from the correct position prior to complete or tight fitting of the cuff around the arm. To prevent such accidental slippage, it has been a normal practice with this sort of the instrument to firstly wrap the cuff around the arm rather loosely and then bring the main body into the correct position where the manometer is readily viewed by the user and finally tighten the cuff for a subsequent blood pressure detecting operation. As above, this procedure is rather cumbersome and therefore renders this instrument to be rather difficult to handle. Alternatively, it may be possible to extend the user's arm into the loop of the cuff already formed by fastening the opposite ends thereof prior to adapting the instrument on the user's arm, but this procedure will also suffer a problem that the main body is not expected to be stable on the arm until the cuff is tightly wrapped around the arm. That is, the above prior instrument fails to be in positive engaging disposition on the arm during the tightening operation of the cuff when wrapping the cuff with the main body resting on the arm or even when extending the arm in the loop of the cuff, and therefore requires a special technique which requires a certain degree of skill acquired only after extended practice or a troublesome procedure for retaining the main body in the correct position until the complete fitting of the instrument on the arm of the user. The sphygmomanometer instrument having a cuff attached to the main body and shaped in the form of a loop is disclosed in U.S. Pat. No. 4,248,242 patented to Tamm. The above shortcomings are also present in this prior art instrument.
In the meanwhile, prior sphygmomanometers incorporating a sound sensor to listen for Korotkoff sounds have in almost all cases an indication of the position of the sensor such that the user can easily adjust the sensor in a correct coincident position with the artery in the arm around which the cuff is wrapped. But, unfortunately there is the fact on the other side that the users who are unfamiliar with the blood pressure measuring scarcely have the knowledge of the exact position of the artery in their arms, so that there frequently occurs a serious failure in the positioning of the sensor, resulting in inaccurate measurement of the blood pressure.
Further, in the instrument disclosed in the above Japanese Utility Model Publication, there is a fear that the one end of the cuff when wrapped around a slender arm may extend on the upper surface of the main body to such an extent as to overlap or conceal the manometer.